To allow reliable execution of process steps on a wire-processing machine, such as insulation-stripping, crimping, and end-fitting, wires that are straight are important.
To make the wires straight, they are generally pulled, with the aid of the drives that are present in the wire-processing machine, through one or more straightening apparatuses that are mounted at the run-in of the machine. Curvatures and twists in the wires are thereby eliminated.
Known straightening apparatuses can require great outlay to yield a given straightening effect. With the usual straightening apparatuses in wire-processing machines, it can be difficult to reproduce a setting on the same straightening apparatus, or on another straightening apparatus, or on another machine.
Known straightening apparatuses usually have a plurality of rolls, between which the wire that is to be straightened is led. They also employ former solution methods for setting the roll-distance, which can use engraved scales and setting screws, in some cases with counters. In some cases, it is also possible to set the roll-distance automatically by means of an actuator. The rolls of the formerly known straightening apparatuses typically sit on two roll-rails. Setting of the pull-in of the straightening apparatus, i.e. the inclination of one or both roll-rails, usually takes place by tight gripping with screws. Frequently, this setting is performed using a rule of thumb which states that the exit-side rolls of the straightening apparatus should touch the wire. Due to the lack of simple setting possibilities and simple setting criteria, the pull-in is often not changed.
For straightening apparatuses there are therefore to date no known simple, robust criteria or parameters which, for example, can be stored together with a wire, so as to make it possible to optimally set the straightening apparatus on an arbitrary machine according to the wire type.
The rolls of straightening apparatuses that are used today are set with simple means to a certain position that depends on the material that is to be straightened. However, this position is very critical. A small incorrect setting, or a small deviation of the external diameter (e.g. caused by production scatter in the wire manufacture), or of the elasticity in the wire (e.g. depending on the temperature when processing), causes greatly differing straightening results.
Inexpensive straightening apparatuses today are set with a parameter, viz, a feeding movement of a rail with rolls perpendicular to the wire.
A straightening apparatus is described in EP0932462 (see also WO 98/12005). This document proposes arrangement of a first row of rolls perpendicular to the axis of the wire. The pull-in results from the arrangement of a second row of rolls which, through being borne in floating manner, is to a small extent additionally modifiable in its angular position. The change in angle is, however, largely undefined, since it is determined by two compression springs, which also serve to open the straightening apparatus. In addition, the pre-tensioning of these springs is modified by adjustment of the distance between the rows of rolls.
A further straightening apparatus is known from EP 0 739 066 A2. The straightening apparatus according to EP 0 739 066 A2 makes use of roll arrangements which, by swiveling movements, are settable in both horizontal and vertical direction.